The Brain Tumor Cooperative Group (BTCG) performs controlled prospective randomized trials in patients with malignant gliomas, based on the concept of multimodality treatment consisting of extensive surgical resection, radiation therapy (RT) and chemotherapy. It is proposed to continue these studies as follows: I. To increase good quality survival by performing clinical trials in newly diagnosed patients and patients with recurrent malignant cerebral gliomas. To complete Phase III Trial 87-01: Two-arm randomized trial in newly diagnosed patients: a) interstitial RT boost plus external RT plus IV BCNU, vs. (b) external RT plus IV BCNU. To continue Phase III Trial 8901: Three-arm randomized trial in newly diagnosed patients and those previously diagnosed and treated with RT without chemotherapy: (a) external RT plus IV BCNU, (b) external RT plus IV BCNU plus 6 doses over 6 months of intra-arterial (IA) cisplatin, (c) RT plus a new drug in a "screening protocol". To plan and perform new trials for patients with recurrent malignant gliomas. Patients with local tumor will be treated with interstitial I- 125 seeds without or with radiosensitization with hyperthermia, hematoporphyrin derivative, radiosensitizer or chemotherapy sensitization. Patients with diffuse tumors will be treated with new chemotherapy, hormonal therapy or immunotherapy. II. To investigate the effect of RT on good quality survival of adult patients with low-grade supratentorial glioma. To continue Phase III Trial 87-30: Two-arm randomized trial in newly diagnosed patients: (a) surgery and immediate RT, vs. (b) surgery and delayed RT. This study is part of an Inter- Group effort. III. To investigate the combination of chemotherapy plus RT in the treatment of primary CNS lymphoma. IV. To investigate RT in the treatment of single brain metastasis post-resection. This study is part of an Inter-Group effort. V. To investigate the antiprogesterone agent, Mifepristone (SU486) in the treatment of unresectable meningioma. This study is part of an Inter-Group effort. VI. To investigate Tumor- Host Biology of human gliomas, including their presentation and evolution in relationship to CT and MRI scans, prognostic variables, and histopathological changes over time. To study evolution and tumor behavior in patients by assessing presenting signs and symptoms in relationship to CT scan and MRI, prognostic variables and histopathological changes over time. VII. To study acute and long-term consequences of therapy, including early and late RT/Chemotherapy neurological and non-neurological effects.